if ( !window.requestAnimationFrame )
{
    window.requestAnimationFrame = (
                                        window.webkitRequestAnimationFrame ||
                                        window.mozRequestAnimationFrame ||
                                        window.msRequestAnimationFrame ||
                                        window.oRequestAnimationFrame ||
                                        function ( callback )
                                        {
                                            return window.setTimeout(callback, 1 /*~ 1000/60*/);
                                        }
                                    );
}